Corvette Glossary Of Terms
The highly successful and versatile 427 cubic inch (426.7cuin) (7.0 L) version of the Mark IV engine was introduced in 1966 as a production engine option for full sized Chevrolets and Corvettes. The bore was increased to 4.25 inches (108 mm), with power ratings varying widely depending on the application. There were smooth running versions with hydraulic lifters suitable for powering the family station wagon, as well as rough idling, high-revving solid lifter models that resembled racing powerplants.
The L-36 engine was produced from 1966-1969, and had 10.25:1 compression, Holley or Q-jet carburetor, nodular iron crankshaft, hydraulic lifters, oval port closed chamber heads, and two-bolt main caps. It produced 385 hp (287 kW) in full-size cars, 390 hp (290 kW) in Corvettes. Corvsport Page References: 1966 Overview, 1968 Overview.
The L-48 V8 was the standard engine in the 1975–1980 Chevrolet Corvette. The L-48 V8 Corvette engine produced 165 bhp in 1975. Power increased to 180 bhp in 1976 and stayed the same in 1977. 1978 saw 175 bhp for California or high altitude areas and 185 bhp for everywhere else. Power increased to 195 bhp in 1979 and decreased to 190 bhp in 1980. Corvsport Page References: 1975 Overview.
Manufactured from 1967-1969, the L68 engine had 10.25:1 compression, Tri-Power, nodular iron crankshaft, hydraulic lifters, aluminum oval port closed chamber heads, and two-bolt main caps. It produced 400 hp (300 kW), and was used exclusively in Corvettes. Corvsport Page References: 1968 Overview.
First introduced in 1966, the L72 engine was the high-performance version of the 427 cubic inch engine, producing 425 horsepower. The engine featured a 4-barrel carburetor, solid-lifters, a more aggressive cam and high flow cylinder heads. Corvsport Page References: 1966 Overview.
The L-79 engine is really nothing more that an L-76 (with 11.0:1 forged pop-up pistons, forged steel rods and crank, 2.02 Corvette heads), but with the 30-30 Duntov cam replaced by the #151 hydraulic cam. The 327-350 hp engine could give many big blocks a run for their money. Corvsport Page References: 1968 Overview.
The L81 was the only 5.7 L (350 cu in) Corvette engine for 1981. It produced 190 bhp and 280 lb-ft of torque from 8.2:1 compression, exactly the same as the 1980 L48, but added hotter cam and computer control spark advance, replacing the vacuum advance. The L81 was unique in that it was the only Corvette engine that employed a “smart carburetor.” The Rochester Quadrajet from 1980 was modified to allow electronic mixture control, and an ECM (Engine Control Module), supplied with data from an exhaust oxygen sensor, modified the fuel/air mixture being fed to the engine. Corvsport Page References: 1981 Overview.
The 1973–1974 L82 was a “performance” version of the Chevy small-block 350 engine that produced approximately 250 brake horsepower (net). It was down to 205 bhp and 255 lb-ft of torque for 1975. It produced 210 bhp in the Corvette for 1976-1977. The 1978 L82 recovered somewhat, producing 220 bhp and 260 lb-ft in the Corvette and in 1979 it produced 225 bhp in the Corvette. In 1980, its final year, it produced a peak of 230 bhp. This engine was also available on the Chevrolet Camaro. Corvsport Page References: 1974 Overview, 1975 Overview, 1976 Overview, 1977 Overview, 1978 Overview, 1979 Overview, 1980 Overview.
The 1982 L83 was the only Corvette engine (and only available with an automatic transmission) producing 200 bhp and 285 lb-ft of torque from 9:1 compression. This was again the only engine on the new 1984 ‘Vette, at 205 bhp and 290 lb-ft of torque. The L83 added Cross-Fire fuel injection (twin throttle-body fuel injection). Since GM did not assign a 1983 model year to production Corvettes, there was also no L83 for 1983. Corvsport Page References: 1982 Overview, 1984 Overview.
The L88 was rated for 430 hp (320 kW) at 5200 rpm. With stock exhaust manifolds and operation in the 6,800 rpm range, it was generally accepted that the engine was capable of producing in excess of 500 Gross HP with free-flowing (open) long tube headers. Corvsport Page References: 1968 Overview.
The L89 engine was an L71 fitted with aluminum heads. While this option produced no power advantage, it did reduce engine (and hence, vehicle) weight by roughly 75 pounds (34 kg). This resulted in superior vehicle weight distribution for improved handling, although any difference in straight line performance was essentially negligible. Corvsport Page References: 1968 Overview.
A new Chevrolet small-block engine, the 1985 L98 included the introduction of tuned-port fuel injection (also known as “TPI”,) which produced 230 hp (172 kW) and 330 lb·ft (447 N·m). It was standard on all 1985–1991 Corvettes. Aluminum cylinder heads (Corvette only) were released midway thru 1986 model run and continued to be used through the end of the L98 Corvette production in 1991. Optional on 87–92 Chevrolet Camaro & Pontiac Firebird models (rated at 225 hp (168 kW)-245 hp (183 kW) and 330 lb·ft (447 N·m)-345 lb·ft (468 N·m, the 1987 versions had 10 hp (7 kW) and 15 lb·ft (20 N·m) more thanks to a 9.5:1 compression and the decision to change to a hydraulic roller camshaft. Compression was increased again in 1991 to 10:1 but output stayed the same. Corvsport Page References: 1985 Overview, 1986 Overview, 1987 Overview, 1988 Overview, 1989 Overview, 1990 Overview, 1991 Overview.
Lear Siegler Incorporated was created as a result of a merger between the Siegler Corporation (Los Angeles) and Lear Avionics Inc. (Santa Monica) that was concluded in 1961. John G. Brooks was the founder; President and Chairman of Siegler and William Lear was the founder; President and Chairman at Lear. The merger was based on Brooks’ goal of growing Siegler into one of the first conglomerates (with a focus on aerospace markets) and Lear’s goal of divesting his ownership interest in Lear to pursue development of his Learjet corporate aircraft (the first pure jet private aircraft). Lear Siegler content courtesy of Wikipedia. Corvsport Page References: 1985 Overview.
The LG4 produced 150 hp (112 kW)-170 hp (127 kW) and 240 lb·ft (325 N·m)-250 lb·ft (339 N·m). The addition of a knock sensor for the engine management system in 1985 allowed an increase in compression and a more aggressive spark timing map in the ECM. As a result power increased for the 1985 models to 165 hp (123 kW) from the 150 hp (112 kW) rating in 1984. Corvsport Page References: 1981 Overview
The LS1 was used in the Corvette from 1997-2004 and was rated at 350HP and 365lb/ft of torque. It was also used in the GM F-Body cars with a rating of 305HP – 325HP. Continuous modifications were made to the LS1 engine throughout its lifetime, pushing engine output up to 382 bhp (285 kW) in the HSV’s YII series, and a Callaway modified version named “C4B” was fitted to HSV GTS models producing 402 bhp (300 kW). Corvsport Page References: 1997 Overview, 1998 Overview.
The LS2 was introduced as the Corvette’s new base engine for the 2005 model year. It produces 400 bhp (300 kW) at 6000 rpm and 400 lb·ft (542 N·m) at 4400 rpm from a slightly larger displacement of 5,967 cc (5.967 L; 364.1 cu in). It is similar to the high-performance LS6, but with improved torque throughout the rpm range. The LS2 uses the “243” casting heads used on the LS6 (although without the sodium filled valves), a smaller camshaft, and an additional 18 cubic inches. The compression of the LS2 was also raised to 10.9:1 compared to the LS1s 10.25:1 and the LS6s 10.5:1. The LS2s in the E-series HSVs are modified in Australia to produce 412 bhp (307 kW) and 412 lbft . The LS2s in the Chevrolet Trailblazer SS and the Saab 9-7X Aero are rated at 395 bhp (295 kW) (2006–2007) or 390 bhp (290 kW) (2008–2009) and 400 lb·ft (542 N·m) of torque due to a different (sometimes referred to as a “truck”) intake manifold that produces more torque at lower RPMs.
The LS2 is also used as the basis of the NASCAR Specification Engine that is used as an optional engine in NASCAR’s Camping World Series East and West divisions starting in 2006, and starting in 2010 may also be used on tracks shorter than two kilometers (1.25 miles) in the Camping World Truck Series. Corvsport Page References: C6 Corvette, 2005 Corvette.
The LS3 was introduced as the Corvette’s new base engine for the 2008 model year. It produces 430 bhp (321kW; 436 PS) at 5900 rpm and 424 lb·ft (575 N·m) at 4600 rpm without the optional Corvette exhaust and is SAE certified. The block is an updated version of the LS2 casting featuring a larger bore of 4.06 in (103 mm) creating a displacement of 6,162 cc (6.162 L; 376.0 cu in). It also features higher flowing cylinder heads sourced from the L92, a more aggressive camshaft with 0.551-inch (14.0 mm) lift, a 10.7:1 compression ratio, a revised valvetrain with 6 mm (0.24 in) offset intake rocker arms, a high-flow intake manifold and 47 lb/hr fuel injectors from the LS7 engine.
The L76/L92/LS3 cylinder heads use 2.165 in (55.0 mm) intake valves, and 1.59 in (40 mm) exhaust valves. Improved manufacturing efficiency makes these heads cheaper than the outgoing LS6 heads, and severely undercuts aftermarket heads. The large valves, however, limit maximum rpm – 6000 in the L76 (with AFM), and 6600 in the LS3 (with hollow stem valves).
In addition to the above, a dual-mode exhaust package with a bypass on acceleration is available. The dual-mode exhaust uses vacuum-actuated outlet valves, which control engine noise during low-load operation, but open for maximum performance during high-load operation. The system is similar to the C6 Z06, but uses a 2.5 in (64 mm) diameter exhaust compared to the Z06’s 3 in (76 mm). Power is boosted to 436 hp (325 kW) and 428 lb·ft (580 N·m) with this option.
From April 2008, Australian performance car manufacturer, HSV, adopted the LS3 as its standard V8 throughout the range, replacing the LS2. The LS3 received modifications for its application to HSV E Series models, producing 425 bhp (317 kW). The LS3 engine in the E Series II GTS (released September 2009) was upgraded to produce 436 bhp (325 kW). All HSV MY12.5 excluding the base Maloo and Clubsport variants have been upgraded to produce 436 bhp (325 kW). Corvsport Page References: 2008 Overview.
Built for the 1971 model year, the LS6 engine was rated at 450 hp (340 kW). It has been suggested that the LS6 was substantially underrated and actually produced well over 500 horsepower (370 kW) as delivered from the factory, although there is no empirical evidence to support this claim. Corvsport Page References:1971 Overview.
The LS7 is a 7,008 cc (7.008 L; 427.7 cu in) engine, based on the Gen IV architecture. The block is changed, with sleeved cylinders and a larger 4.125in (104.775mm) bore and longer 4.00in (101.6mm) stroke than the LS2. The small-block’s 4.4 in (110 mm) bore spacing is retained, requiring pressed-in cylinder liners. The crankshaft and main bearing caps are forged steel for durability, the connecting rods are forged titanium, and the pistons are hypereutectic. The two-valve arrangement is retained, though the titanium intake valves by Del West have grown to 2.20 in (56 mm) and sodium-filled exhaust valves are up to 1.61 in (41 mm).
Peak output is 505 hp (377 kW) at 6300 rpm and 470 lb·ft (640 N·m) at 4800 rpm with a 7100 rpm redline During GM’s reliability testing of this engine in its prototype phase, the LS7 was remarked to have been repeatedly tested to be 8000 rpm capable, although power was not recorded at that rpm level, due to the constraints of the camshaft’s hydraulic lifters and the intake manifold ability to flow required air at that engine speed.
The LS7 is hand-built by the General Motors Performance Build Center in Wixom, Michigan. Most of these engines are installed in the Z06, some are also sold to individuals by GM as a crate engine. Corvsport Page References: 2006 Corvette.
Built from 1970–1972, the LT-1 was the ultimate 350 cu in V8, becoming available in 1970. It used solid lifters, 11:1 compression, the ‘178’ high-performance camshaft, and a 780 CFM Holley four-barrel carburetor on a special aluminum intake, with rams’ horn exhaust manifolds in the Chevrolet Corvette, Delco transistor ignition and a low-restriction exhaust factory rated at 370 bhp in early Corvette sales literature, but actually only sold as 360 bhp version at 6000 rpm and 380 lb-ft at 4000 (the NHRA rated it at 425 hp for classification purposes). Redline was 6500 rpm but power fell off significantly past 6200 rpm. The LT-1 was available in the Corvette, Corvette ZR-1, and Camaro Z28. Power was down in 1971 to dual-rated 330 bhp, 255 nethp and 360 lb-ft of torque with 9:1 compression, and again in 1972 (the last year of the LT-1, now rated using net only, rather than gross, measurement) to 255 bhp and 280 lb-ft. Content courtesy of Wikipedia. Corvsport Page References: 1970 Overview, 1971 Overview, 1972 Overview.
In 1992, GM created a new-generation small-block engine called the LT1, similar to the high-output Generation I LT-1 of the 1970s. It displaced 5.7 L (350 cu in) and was a 2-valve pushrod design. Making its debut in the 1992 Chevrolet Corvette, the new LT sought to draw upon the heritage of the ultimate small-block, the 1970 Chevrolet LT-1. It displaced 5.7 L (350 cu in) and was a 2-valve pushrod design. The LT1 used a reverse-flow cooling system which cooled the cylinder heads first, maintaining lower cylinder temperatures and allowing the engine to run at a higher compression than its immediate predecessors. (LT1 Engine content courtesy of Wikipedia. Corvsport Page References: 1992 Overview, 1993 Overview, 1994 Overview, 1995 Overview, 1996 Overview.
The LT4 was a special high-performance version of the new-generation LT1. With the addition of a slightly more aggressive camshaft profile, 1.6:1 roller aluminum rocker arms, high-flow cylinder heads, and an intake manifold (painted red) port matched to the raised port LT4 cylinder heads, it was rated at 330 horsepower (250 kW) and 340 lb·ft (461 N·m). It was introduced in the 1996 model year, for the last year of the C4 Corvette, and came standard on all manual transmission (ZF 6-speed equipped) C4 Corvettes. The engine was passed down to special versions of the Camaro and Firebird the next model year. (LT4 Engine content courtesy of Wikipedia. Corvsport Page References: 1996 Overview.
For the 1990 model year, Chevrolet released the Corvette ZR-1 with the radical overhead cam LT5 engine, which shared only the 4.4 inch bore spacing with any previous LT engine. The LT5 was engineered by Lotus Engineering in the United Kingdom. The design team was headed by project manager David Whitehead. The engine was an all-aluminum 5.7 L (349 cu in) small-block V8, but was thoroughly different from other Chevrolet 350 engines. The LT5’s bore and stroke was 3.9 by 3.66 in (99 by 93 mm) instead of the usual 4 by 3.48 in (102 by 88 mm) and it featured Lotus-designed 32-valve DOHC heads. It was hand built by specialty engine builder Mercury Marine in Stillwater, Oklahoma. The LT5 engine produced 375 horsepower (280 kW) and 370 lb·ft (502 N·m) during the production run of the 1990-1992 Corvette ZR-1s, but later jumped to 405 horsepower (302 kW) and 385 lb·ft (522 N·m) the 1993 thru 1995 models, thanks to cam timing changes and improvements to the engine porting. The 1993 LT5 also added 4-bolt main bearing caps and an exhaust gas recirculation system.
The engine was used only in ZR-1 Corvettes. The LT5 was very expensive, and after just six years of production, GM canceled the ZR-1 option. A total of 6,939 were produced. Despite its limited production, the LT5 however wasn’t an evolutionary dead end. Despite being discontinued, a new class of premium V8’s for Cadillac (and eventually Oldsmobile,) which featured a dual overhead cam for the V8 Northstar engine (and its derivatives,) drew heavily from the LT5’s design and lessons learned from its production. Corvsport Page References: 1993 Overview.
A native of Duluth, MN, where his first job was delivering daily newspapers, Robert Lund joined Chevrolet’s district office in Minneapolis in 1946, after a stint as a Navy lieutenant in the Pacific during World War II. He rose through the Chevrolet ranks to Division General Manager. During his eight year in that role, the Chevrolet division of GM sold a record 21 million cars and trucks. From the Chevrolet helm, he moved to the post of general manager at Cadillac.
His gregarious personality was well-known to dealers. He had what they called a super salesman’s style, but without being overly aggressive. Retiring from GM in 1985 as an executive vice president, Mr. Lund opened a new Cadillac store in Phoenix two years later at age 67. Among his innovative marketing initiatives were monthly showroom lunches for Cadillac owners, catered by the city’s best restaurants. Corvsport Page References: 1979 Overview.